Devices and techniques for treating neurological disorders by drug infusion and by electrical stimulation of a person's central nervous system are well known in the prior art. For instance, U.S. Pat. No. 5,713,922 to King, 5,782,798 to Rise, and U.S. Pat. No. 5,814,014 to Elsberry et al., each assigned to Medtronic, Inc. of Minneapolis, Minn., disclose such devices and techniques and are hereby incorporated by reference.
Such treatment devices and techniques often employ drug-infusion pumps and/or electrical pulse generators that are implanted within a patient's body. Accordingly, available memory for storing the parameters, such as treatment dose, duration, and timing, of various treatment protocols is severely limited. As a result, known implantable treatment devices are capable of storing a treatment protocol via telemetry that implements only a single treatment mode, such as single bolus, simple continuous, periodic bolus, or complex continuous treatment protocols. Single bolus refers to a non-recurring, finite treatment period. Simple continuous is a continuous treatment at a fixed treatment level. Periodic bolus refers to a single periodically recurring finite treatment period. Complex continuous refers to a plurality of treatment periods that periodically repeat themselves.
FIG. 2 depicts a prior art manner of specifying a complex continuous treatment protocol. The vertical axis represents the treatment rate. The horizontal axis represents elapsed time from the treatment protocol having been downlinked to the treatment device. In FIG. 2, the location of the vertical axis along the horizontal axis represents the time at which the treatment protocol was downloaded to the treatment device, as depicted at 100. For each example given in this document, the time at which the treatment prescription was downlinked to the treatment device will be assumed to be 3:00 PM, local time. In FIG. 2, a complex continuous treatment protocol is depicted in which a background rate of 20 microliters/hour is infused, as depicted at 102-1 through 102-8 (collectively 102). Note that, while the examples refer to infusion protocols, they are equally applicable to stimulation protocols. Background rate 102 is in effect when no treatment step is being performed.
The complex continuous treatment protocol depicted in FIG. 2 has the additional following attributes: the treatment cycle time is 24 hours; between 6:00 AM and 8:00 AM, 600 microliters is infused; between 11:00 AM and 1:00 PM, 200 microliters is infused; and between 9:00 PM and 11:00 PM, 500 microliters is infused.
In order to program such a treatment protocol using known prior art methods, treatment step 104-1, which corresponds to the 500 microliter treatment step from 9–11 PM, is programmed to start after a delay of 6 hours from the time the protocol is downlinked to the treatment device, namely, 3:00 PM. The treatment rate is determined by dividing the dose by the treatment-step duration, in this case 500 microliters divided by 2 hours, which is 250 microliters/hour. Accordingly, treatment step 104-1 would be programmed to include a delay from downlinking of 6 hours, during which the background treatment rate would be in effect, as depicted by 102-1. Treatment step 104-1 would also be programmed to provide treatment at 250 microliters/hour for 2 hours. Similarly, treatment step 106-1 would be programmed to include a delay from the completion of treatment step 104-1 of 7 hours, during which background treatment 102-2 would be in effect, and treatment at 300 microliters/hour for 2 hours. Treatment step 108-1 would be programmed to include a delay from the completion of treatment step 106-1 of 3 hours, during which background treatment 102-3 would be in effect, and treatment at 100 microliters/hour for 2 hours.
Following the completion of treatment step 108-1, background rate 102-4 would be in effect for the remaining 2 hours of the 24-hour treatment cycle.
Then, the 24-hour cycle would repeat itself in perpetuity or until a new treatment protocol is downlinked to the treatment device. Accordingly, background rates 102-5 through 102-8 of the second 24-hour treatment cycle shown in FIG. 2 correspond to background rates 102-1 through 102-4, respectively, of the first 24-hour treatment cycle shown in FIG. 2. Similarly, treatment steps 104-2, 106-2, and 108-2 of the second 24-hour treatment cycle shown in FIG. 2 correspond to treatment steps 104-1, 106-1, and 108-1, respectively, of the first 24-hour treatment cycle shown in FIG. 2.
Such known methods of specifying treatment protocols undesirably require that each time a change from one infusion mode, such as single bolus, simple continuous, periodic bolus, or complex continuous, to another infusion mode is desired, the new treatment protocol must be downlinked to the treatment device. In other words, known implantable treatment devices are incapable of storing multiple treatment-mode protocols. Patients and physician-programmers of such treatment devices are therefore severely inconvenienced by having to re-program such treatment devices each time an infusion mode change is made.